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Development of a multimodal anthropomorphic liver phantom for the improvement of navigated tumour treatment

Ruitenbeek, H.C. (2019) Development of a multimodal anthropomorphic liver phantom for the improvement of navigated tumour treatment.

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Abstract:In liver surgery, new technologies and equipment are introduced to aid the surgeon in finding diagnosed lesions and achieving successful resection. To support the development of surgical navigation technologies and provide a simulation setting for researchers and surgeons, a multimodal, patient-specific liver phantom needs to be developed. The phantom needs to consist of substitute structures for parenchyma, vasculature and tumours. The geometry should be patient-specific which means the size and outline of the liver, together with vasculature and lesions, are based on human anatomy and resemble a specific case. First, material selection was performed to select the substitute materials to build the phantom. Criteria where realistic ultrasound contrast of parenchyma, vasculature and tumours. For MRI the contrast must be sufficient for vasculature and tumour segmentation to create a 3D model, using the same method as in patient scans. Candle gel was found to be the best material to create a realistic ultrasound aspect of liver parenchyma based on intensity differences and mechanical properties. For vasculature, cavities filled with water show the best resemblance to human liver vasculature. The hollow vasculature was created by extracting a 3D printed vasculature model after casting the candle gel. The combination of candle gel parenchyma and hollow vasculature can clearly be distinguished on MRI and therefore can produce a 3D model similar to a preoperative model used in surgery. Tumours consist of a mixture of candle gel and carnauba wax to realize ultrasound and MRI contrast with the parenchyma substitute. Finally, a patient-specific-liver phantom was created with the selected materials and validated by comparison to the patient model it was based on. The parenchyma was shaped using a 3D printed mold of the liver outline. In this mold the 3D printed vasculature model together with the tumour were placed. The candle gel was poured into the sealed mold to realize the phantom. The phantom shows high geometrical resemblance with a volume difference of 66 cm3 and a 95-percentile Hausdorff distance of 5.7 mm. The hepatic and portal vasculature show corresponding bifurcations. Practical use of the phantom shows that it is useful for performing US to MRI registrations and use of ultrasound guided ablation equipment. Successful positioning of tumours was not achieved and the phantom is very fragile. Challenges to be overcome in future research are accomplishing accurate tumour placement and applying a protective element to enlarge the durability of the phantom.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
Link to this item:http://purl.utwente.nl/essays/81528
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